The present invention relates to a straight-action breech block system for a tubular automatic weapon. The breech block system is of the type which has a housing and a rotary head guided therein for a longitudinal and rotational movement. The rotary head is provided with a locking member having external teeth to provide a bayonet-like lock for the breech block in an internally toothed region at the end of the gun barrel. The breech block system further includes an inductive ignition device integrated in the breech block for igniting a cartridge disposed in a chamber of the gun barrel.
A breech block assembly of the above-outlined type is disclosed, for example, in German Patent No. 2,443,044 to which corresponds U.S. Pat. No. 3,969,983. The breech block assembly disclosed therein includes a housing accommodating a head provided with a locking flange having external circumferential teeth. In order to lock the breech block the rotary head is able to engage in a mating toothed flange which is associated with the gun barrel and which has internal teeth offset by one tooth pitch. A firing pin is provided in the rotary head to ignite a cartridge disposed in the chamber of the gun barrel according to the percussion ignition principle.
Such a breech block however, is not suitable for use with ammunition without metal casings (caseless, cartridged ammunition) since a firing pin of the above-described type, in view of the firing stresses acting thereon, is subject to substantial wear and may cause a cook-off of the subsequently supplied caseless cartridges. In the prior art identified above, the sealing problems occurring when firing caseless, cartridged ammunition, compared to ammunition having metal casings, are not considered, so that the disclosed breech block assembly does not have a suitable sealing configuration.
While, in order to improve the ignition of caseless ammunition, electrical ignition means have been proposed for such breech block systems, because of the back and forth movement of the breechblock, problems of supplying the required electrical energy from an energy source external to the weapon are encountered. In addition to the general problems of supplying the breech block assembly with electrical energy, an electrical contact pin ignition is unsuitable for caseless ammunition since such a contact pin, similarly to the percussion ignition pin, wears easily and tends to become scaly which, in turn, prevents clean contacting and increases the susceptibility to malfunctions.